When the JSmooth plugin is the only plugin in a build, it does not create the target folder itself, and fails with:
[INFO] Using jsmooth file... D:\Workspaces\DatabaseTool-assembly\src\main\jsmooth\databasetool.jsmooth
[INFO] Setting jar name to :DatabaseTool-assembly-4.3-SNAPSHOT.jar
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Cannot create temporary directory
[INFO] ------------------------------------------------------------------------